Two senior Commonwealth officials have complained formally about the Gillard government's razor gang, warning it may render them unable to do their jobs.

The Australian Bureau of Statistics also warned staff yesterday it would retrench up to 75 employees, saying it intended to target Canberra-based workers.

In letters tabled in parliament yesterday, Human Rights Commission president Catherine Branson and information commissioner Professor John McMillan argued their agencies should be spared the record-high ''efficiency dividend'' of 4 per cent, an annual cut to administrative spending.

The government has urged the bureaucracy to refrain from shedding staff where possible and to instead cut spending on travel, legal services and advertising.

However, Ms Branson said her commission spent little on those areas, and pleaded for her agency to be exempted from the cuts, as were other federal courts and tribunals.

She said the extra dividend would place the commission ''in a singularly embarrassing position'' and force it to direct funding ''away from the purposes for which it was provided to us''.

Professor McMillan said he, too, would have little choice but to cut jobs.

''If we are forced to further reduce [Office of the Information Commissioner] staff numbers, I hold a genuine concern that we will not be able to discharge our functions effectively.''

His office was already struggling to work through a large backlog of requests to review freedom of information decisions, he said.

''I believe that it will be embarrassing both to the reputation of the office and the success of the new open government measures if we are unable through staffing pressures to reduce the backlog.''

Meanwhile, the Bureau of Statistics warned it would soon retrench 50 to 75 employees.

Australian statistician Brian Pink told his 3540 staff the voluntary redundancies would be offered to those employed below executive level 2, adding that ''priority will be given to central office [ACT-based] employees, as this is where we need to reduce our expenditure''.

Community and Public Sector Union national secretary Nadine Flood said Dr Pink's announcement was ''proof positive'' that the government's spending cuts were costing jobs.

''We expect to see similar announcements in coming months as other public sector departments struggle to cut their budgets ... We are increasingly concerned that the government's relentless program of cuts will drive talented and experienced staff out of the workforce.''

The Health Department also announced late last year it would need to retrench staff to deal with the government's economy drive.

ACT Liberal senator Gary Humphries said last night agencies were ''seriously concerned'' that the latest efficiency dividend would cripple their capacities.